Answer:
The correct answer is b. He determined that DNA contains four nitrogenous bases.
Explanation:
Levene was an American biochemist who studied the structure of DNA in the early 1900s and in 1920 he found that DNA consists of four nitrogenous bases that are Adenine, Guanine, Thymine, Cytosine.
He also found deoxyribose sugar and phosphate group and said that nucleotide is the basic unit of DNA which contains a ribose sugar with attached nitrogenous base and phosphate group.
He also concludes that an equal amount of adenine, guanine, thymine, and cytosine makes the DNA which is now known as tetranucleotide hypothesis. So the correct answer is b. He determined that DNA contains four nitrogenous bases.
<span>Sputum membranes tests are used to test the lungs, trachea and bronchial canals for pathogens that can have an adverse affect on the lungs. These pathogens can cause infections that can have serious effects on your breathing and all over health.</span>
Answer:
in the west hope this helps
Explanation:
Answer:
In thermodynamics, a closed system can be described as a system which can exchange energy from outside but matter cannot be transferred from such a system. This means that the resources present on the Earth cannot be transferred or replaced and the waste can also not be removed. By understanding the concept of the closed system, humans should recognize the fact that many resources such as minerals present on the Earth cannot be replaced and hence, resources should be utilized effectively in a conserved manner. Also, as waste cannot be removed hence humans should stop forming such waste products which cannot be removed or recycled.
